Kyrk Kyz Kala, Sth Karakalpakstan, Uzbekistan

Sultanuizdag ridge covers the lands of lower Khorezm only from the north. This is why the chain of frontier defenses was built during Siyavushids in the 4th–3rd centuries BC to defend the north-eastern and eastern borders.

The remains of these fortresses are now known as Ayazkala I, minor and major Kyrk Kyz Kala, Kurgashin Kala, Djanbas Kala and Major Guldursun. From the height of Ayaz Kala I the nearest fortresses: Minor and Major Kyrk Kyz Kala can be seen clearly. Major Kyrk Kyz is located near the road. There are the remains of highly fortified fortress (250x215m) with the walls of up to 12 meters high. It defended one of the main channels of ancient Khorezmian oasis till the 8th century.

Due to the second walls row inside the fortress there was a two-tier gallery for archers. Over the perimeter the walls were strengthened by rectangular towers with three-tier inner premises. In each corner of the fortress there were two towers in composition known as "dovetail". In the distance of 10 meters from the main walls Major Kyrk Kyz Kala had the exterior protective wall - proteichisma.